From: NeilBrown Date: Thu, 13 Dec 2012 04:14:36 +0000 (+1100) Subject: NFS: avoid NULL dereference in nfs_destroy_server X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=f259613a1e4b44a0cf85a5dafd931be96ee7c9e5;p=linux-edison.git NFS: avoid NULL dereference in nfs_destroy_server In rare circumstances, nfs_clone_server() of a v2 or v3 server can get an error between setting server->destory (to nfs_destroy_server), and calling nfs_start_lockd (which will set server->nlm_host). If this happens, nfs_clone_server will call nfs_free_server which will call nfs_destroy_server and thence nlmclnt_done(NULL). This causes the NULL to be dereferenced. So add a guard to only call nlmclnt_done() if ->nlm_host is not NULL. The other guards there are irrelevant as nlm_host can only be non-NULL if one of these flags are set - so remove those tests. (Thanks to Trond for this suggestion). This is suitable for any stable kernel since 2.6.25. Cc: stable@vger.kernel.org Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust --- diff --git a/fs/nfs/client.c b/fs/nfs/client.c index c285e0a117e..9f3c66438d0 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -615,8 +615,7 @@ EXPORT_SYMBOL_GPL(nfs_create_rpc_client); */ static void nfs_destroy_server(struct nfs_server *server) { - if (!(server->flags & NFS_MOUNT_LOCAL_FLOCK) || - !(server->flags & NFS_MOUNT_LOCAL_FCNTL)) + if (server->nlm_host) nlmclnt_done(server->nlm_host); }